Here's an idea on how you can change powder bushings on the charge bar without having to take the whole upper assembly off and emptying the powder. This only works if you are NOT using birdshot or anything in the shot hopper.

Before you do this, you want to mark the left and right sides of the powder drop hole on the black die and carrier assembly, just below the charge bar. That way, you take the name plate off, slide the charge bar all the way to the right (make sure to catch that last powder throw!), and then pull out the RIGHT end of the charge bar out towards you while keeping the left end situated under the powder drop hole. Change the bushing and reverse everything.